Documentation  › java.nio  › LongBuffer
 
 


  LongBuffer
  public abstract

  Inherits From:   Buffer : Object
  Conforms To:   Comparable
  Declared In:   java.nio


Class Description
 
A long buffer.

This class defines four categories of operations upon long buffers:

  • Absolute and relative get and put methods that read and write single longs;

  • Relative get methods that transfer contiguous sequences of longs from this buffer into an array; and

  • Relative put methods that transfer contiguous sequences of longs from a long array or some other long buffer into this buffer; and

  • Methods for compacting, duplicating, and slicing a long buffer.

Long buffers can be created either by allocation, which allocates space for the buffer's content, by wrapping an existing long array into a buffer, or by creating a view of an existing byte buffer

Like a byte buffer, a long buffer is either direct or non-direct. A long buffer created via the wrap methods of this class will be non-direct. A long buffer created as a view of a byte buffer will be direct if, and only if, the byte buffer itself is direct. Whether or not a long buffer is direct may be determined by invoking the isDirect method.

Methods in this class that do not otherwise have a value to return are specified to return the buffer upon which they are invoked. This allows method invocations to be chained.



Class Variables
 
None declared in this class.


Instance Variables
 
None declared in this class.


Constructors
 
None declared in this class.


Class Methods
 
allocate
public static LongBuffer allocate( int capacity )

Allocates a new long buffer.

The new buffer's position will be zero, its limit will be its capacity, and its mark will be undefined. It will have a array, and its offset will be zero.


wrap
public static LongBuffer wrap( long[] array )

Wraps a long array into a buffer.

The new buffer will be backed by the the given long array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer's capacity and limit will be array.length, its position will be zero, and its mark will be undefined. Its array will be the given array, and its offset will be zero.




wrap
public static LongBuffer wrap( long[] array, int offset, int length )

Wraps a long array into a buffer.

The new buffer will be backed by the the given long array; that is, modifications to the buffer will cause the array to be modified and vice versa. The new buffer's capacity will be array.length, its position will be offset, its limit will be offset + length, and its mark will be undefined. Its array will be the given array, and its offset will be zero.



Instance Methods
 
array
public final long[] array( )

Returns the long array that backs this buffer  (optional operation).

Modifications to this buffer's content will cause the returned array's content to be modified, and vice versa.

Invoke the hasArray method before invoking this method in order to ensure that this buffer has an accessible backing array.




arrayOffset
public final int arrayOffset( )

Returns the offset within this buffer's backing array of the first element of the buffer  (optional operation).

If this buffer is backed by an array then buffer position p corresponds to array index p + arrayOffset().

Invoke the hasArray method before invoking this method in order to ensure that this buffer has an accessible backing array.




asReadOnlyBuffer
public abstract LongBuffer asReadOnlyBuffer( )

Creates a new, read-only long buffer that shares this buffer's content.

The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer; the new buffer itself, however, will be read-only and will not allow the shared content to be modified. The two buffers' position, limit, and mark values will be independent.

The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer.

If this buffer is itself read-only then this method behaves in exactly the same way as the duplicate method.




compact
public abstract LongBuffer compact( )

Compacts this buffer  (optional operation).

The longs between the buffer's current position and its limit, if any, are copied to the beginning of the buffer. That is, the long at index p = position() is copied to index zero, the long at index p + 1 is copied to index one, and so forth until the long at index limit() - 1 is copied to index n = limit() - 1 - p. The buffer's position is then set to n+1 and its limit is set to its capacity. The mark, if defined, is discarded.

The buffer's position is set to the number of longs copied, rather than to zero, so that an invocation of this method can be followed immediately by an invocation of another relative put method.




compareTo
public int compareTo( Object ob )

Compares this buffer to another object.

Two long buffers are compared by comparing their sequences of remaining elements lexicographically, without regard to the starting position of each sequence within its corresponding buffer.

A long buffer is not comparable to any other type of object.




duplicate
public abstract LongBuffer duplicate( )

Creates a new long buffer that shares this buffer's content.

The content of the new buffer will be that of this buffer. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.

The new buffer's capacity, limit, position, and mark values will be identical to those of this buffer. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.




equals
public boolean equals( Object ob )

Tells whether or not this buffer is equal to another object.

Two long buffers are equal if, and only if,

  1. They have the same element type,

  2. They have the same number of remaining elements, and

  3. The two sequences of remaining elements, considered independently of their starting positions, are pointwise equal.

A long buffer is not equal to any other type of object.




get
public abstract long get( )

Relative get method. Reads the long at this buffer's current position, and then increments the position.




get
public abstract long get( int index )

Absolute get method. Reads the long at the given index.




get
public LongBuffer get( long[] dst )

Relative bulk get method.

This method transfers longs from this buffer into the given destination array. An invocation of this method of the form src.get(a) behaves in exactly the same way as the invocation 

 
src.get(a, 0, a.length)



get
public LongBuffer get( long[] dst, int offset, int length )

Relative bulk get method.

This method transfers longs from this buffer into the given destination array. If there are fewer longs remaining in the buffer than are required to satisfy the request, that is, if length > remaining(), then no longs are transferred and a BufferUnderflowException is thrown.

Otherwise, this method copies length longs from this buffer into the given array, starting at the current position of this buffer and at the given offset in the array. The position of this buffer is then incremented by length.

In other words, an invocation of this method of the form src.get(dst, off, len) has exactly the same effect as the loop 

 
for (int i = off; i < off + len; i++) 
dst[i] = src.get();
except that it first checks that there are sufficient longs in this buffer and it is potentially much more efficient.




hasArray
public final boolean hasArray( )

Tells whether or not this buffer is backed by an accessible long array.

If this method returns true then the array and arrayOffset methods may safely be invoked.




hashCode
public int hashCode( )

Returns the current hash code of this buffer.

The hash code of a long buffer depends only upon its remaining elements; that is, upon the elements from position() up to, and including, the element at limit() - 1.

Because buffer hash codes are content-dependent, it is inadvisable to use buffers as keys in hash maps or similar data structures unless it is known that their contents will not change.




isDirect
public abstract boolean isDirect( )

Tells whether or not this long buffer is direct.




order
public abstract ByteOrder order( )

Retrieves this buffer's byte order.

The byte order of a long buffer created by allocation or by wrapping an existing long array is the order of the underlying hardware. The byte order of a long buffer created as a view of a byte buffer is that of the byte buffer at the moment that the view is created.




put
public abstract LongBuffer put( int index, long l )

Absolute put method  (optional operation).

Writes the given long into this buffer at the given index.




put
public abstract LongBuffer put( long l )

Relative put method  (optional operation).

Writes the given long into this buffer at the current position, and then increments the position.




put
public final LongBuffer put( long[] src )

Relative bulk put method  (optional operation).

This method transfers the entire content of the given source long array into this buffer. An invocation of this method of the form dst.put(a) behaves in exactly the same way as the invocation 

 
dst.put(a, 0, a.length)



put
public LongBuffer put( long[] src, int offset, int length )

Relative bulk put method  (optional operation).

This method transfers longs into this buffer from the given source array. If there are more longs to be copied from the array than remain in this buffer, that is, if length > remaining(), then no longs are transferred and a BufferOverflowException is thrown.

Otherwise, this method copies length longs from the given array into this buffer, starting at the given offset in the array and at the current position of this buffer. The position of this buffer is then incremented by length.

In other words, an invocation of this method of the form dst.put(src, off, len) has exactly the same effect as the loop 

 
for (int i = off; i < off + len; i++) 
dst.put(a[i]);
except that it first checks that there is sufficient space in this buffer and it is potentially much more efficient.




put
public LongBuffer put( LongBuffer src )

Relative bulk put method  (optional operation).

This method transfers the longs remaining in the given source buffer into this buffer. If there are more longs remaining in the source buffer than in this buffer, that is, if src.remaining() > remaining(), then no longs are transferred and a BufferOverflowException is thrown.

Otherwise, this method copies n = src.remaining() longs from the given buffer into this buffer, starting at each buffer's current position. The positions of both buffers are then incremented by n.

In other words, an invocation of this method of the form dst.put(src) has exactly the same effect as the loop 

 
while (src.hasRemaining()) 
dst.put(src.get());
except that it first checks that there is sufficient space in this buffer and it is potentially much more efficient.




slice
public abstract LongBuffer slice( )

Creates a new long buffer whose content is a shared subsequence of this buffer's content.

The content of the new buffer will start at this buffer's current position. Changes to this buffer's content will be visible in the new buffer, and vice versa; the two buffers' position, limit, and mark values will be independent.

The new buffer's position will be zero, its capacity and its limit will be the number of longs remaining in this buffer, and its mark will be undefined. The new buffer will be direct if, and only if, this buffer is direct, and it will be read-only if, and only if, this buffer is read-only.




toString
public String toString( )

Returns a string summarizing the state of this buffer.



Known Subclasses
 
None.



 
 
  dydoc
  3/10/05